A rotary position sensor is used in vehicle transmissions to determine what gear is engaged, e.g., park, reverse, neutral, drive and low (PRNDL). Information provided by the position sensor helps control some vehicle functions, such as lights, and can prevent vehicle start while in the wrong gear.
The dirty, vibrating, high temperature, fluid-filled chambers of a transmission make it a harsh environment, unsuitable for most types of angular position sensor technologies. Many existing rotary position (especially magnetic), sensors capable of this environment have large linearity error due to their rotating nature, which must be compensated for by electronics. In addition, the manufacturing and use of vehicles can often result in metallic debris. Many conventional magnetic position sensors collect this debris that must be cleaned off to operate effectively. Conventional rotary position sensors for this type of application also have less efficient magnetic circuits.
There is a need to provide a rotary position sensor that has a magnet with a reduced footprint so that it is less likely to attract debris, while having a magnetic circuit that is stronger and more efficient than conventional rotary position sensor magnetic circuits.